See the www.whitehouse.org story at TechPresident.com, here is the excerpt:

WhiteHouse.gov has gone Drupal. After months of planning, says an Obama Administration source, the White House has ditched the proprietary content management system that had been in place since the days of the Bush Administration in favor of the latest version of the open-source Drupal software, as the AP alluded to in its reporting several minutes ago.